The invention relates to a local terminal connected to a telecommunication network for communicating in the simultaneous bidirectional connected mode with at least one distant terminal.
The invention also relates to an automatic recall procedure which is put into operation by a local terminal after an effort to establish connection with a distant terminal has failed, the relevant terminals being connected to a telecommunication network and identified in the network by respective addresses and/or connection numbers.
The invention finally relates to a telecommunication system comprising at least one terminal referred to as local terminal and one terminal referred to as distant terminal which are capable of communicating in the simultaneous bidirectional connected mode.
A procedure for carrying out a repeat call request in a private telephone exchange controlled by a stored program is known from PCT patent application no. WO 95/20858 with German priority. This document describes the implementation of an automatic recall procedure available for communications between an internal subscriber of the private network and an external subscriber, based on a telephone exchange which already has this function for the internal communications.
This procedure can only be realized from a terminal connected to a telephone exchange which is provided with the desired function. It is not applicable from a terminal connected to a public network which does not offer this function.
It is an object of the invention, therefore, to provide means for achieving an automatic recall function integrated in a terminal of a telecommunication network, provided with a data transfer protocol which operates in the simultaneous bidirectional mode.
To achieve this object, a terminal as mentioned in the opening paragraph is characterized in that it comprises an integrated automatic recall device provided with a local command which is to be activated after an effort to establish a connection with a distant terminal has failed, so as to repeat automatically the effort until said connection has been established, while staying within the limit of a given number of repeat operations.
Similarly, a procedure as mentioned above is characterized in that it comprises the following steps:
storage of the address and/or the number of the distant terminal,
realization of a finite loop for repeating said effort to establish a connection with the address and/or the number stored,
detection of a positive result if a connection has been established, and of a negative result if it has not,
if the result is positive, transmission of connection signals for informing each terminal that the connection has been established,
if the result is negative, transmission of a result signal for informing the local terminal that the connection effort has failed.
Finally, a system as mentioned above is characterized in that the local terminal comprises an integrated automatic recall device provided with a local command which is activated after an effort to establish connection with a distant terminal has failed, for the purpose of automatically repeating said effort until the connection has been established, while staying within the limit of a given number of repeat operations.
In a particularly advantageous embodiment applied to the field of mobile telephony, the invention renders it possible to reduce considerably the number of unsuccessful calls to a distant mobile terminal. Indeed, in certain regions where the radio infrastructure does not render it possible to carry the traffic correctly, especially in Singapore, the failure rate for the first call lies close to 100%.
The invention provides a mobile terminal fitted with an automatic recall function which is designed to improve the success rate of efforts to establish a connection with a distant mobile terminal via a mobile telephone network.
According to a major characteristic of the invention, therefore, a terminal, a procedure, and a system as defined respectively above are designed to operate by a mobile telephone standard of the GSM type (Global System for Mobile Communications), and in particular in conformity with a recommendation of the type ETS 300 505, Annex A, dated January 1996, of the ETSI (European Telecommunications Standards Institute), relating to the restriction of automatic repeat calls.